To be honest I would just use a fuse (maybe with my own custom graphic) if you want to show the breaker as being tripped you can edit a fuse and change it to 'Simulate as Blown'. The only reason I would consider using a switch is if I was going to do a lot of simulation and constantly needed to change the state of the circuit breaker.
If you need to create a custom component the process is simple.
1. Place the components to require and connect them together.
2. From the Drawing menu, click 'Write Block'
3. Select a Base Point (or insertion point)
4. Select the objects that you want to save choosing the from the options of what you want to do with the original objects/entities (I.e. keep them delete them)
5. Set the path where you want to save the Block to (normally the VeSys Blocks directory)
6. Click OK
You can then place this into any drawing using the 'Insert Block' command just remember to explode this on or after you have inserted it otherwise it will be one object. If you have a library part you can add the dwg name of the block to a library part so whenever the part number is selected it will pick your custom graphics rather than the standard VeSys symbol.